I noticed this too, he made comments expecting a response and nothing happened, crickets.
Crickets because the mics were set up so you couldn’t hear. He received applause and photos were taken. He also spoke about issues.
Cruz speech...
https://www.youtube.com/watch?v=0tJVNfdP9dA
DT speech...
https://www.youtube.com/watch?v=K0HBmB9kypU